Aftermarket focus screens & auto exposure

[douglas_r._cain]

I am looking at getting an aftermarket focus screen (such as Beattie, etc) and am wondering how this will affect auto-exposure prisms.

Since the viewfinder screen will be X-stops brighter, and (I assume) the AE prism finder is also "looking" at this same and now brighter screen, won't you have to

adjust the exposure to say -1 1/3 stops (or whatever) on EVERY meter reading

to adjust for the extra brightness? Specifically, I'm looking at getting a Mamiya RZ with AE prism finder, and a bright focus screen since I'm looking at available light photography. And I was just wondering how AE prisms work with aftermarket screens. Thanks.

[chris_patti]

Yes, brighter aftermarket viewing screens will affect the reading of ttl meters that read through the screen. The easiest way to deal with this is by adjusting the ASA setting of your meter. So, if your aftermarket screen is 2 stops brighter than the original, set ASA 2 stops slower than the film you are using. E.g., if you normally set ASA at 100 for a particular film, use 25 instead. Of course, if you use really slow film, this may not be practical on some meters. If you normally do tests to establish a personal exposure index for the films you use, it's probably best just to re-do them with the new screen in place.

[jim_lakey]

Beattie Systemss Inc. has recently stopped producing and selling focusing screens. Brightscreen offers a wide of screens for all types of cameras. Meter compensation is extremely minimum. You can reach Brightscreen at 800 235-2451 local and international 423 478-1451 or visit web site at:

 

<p>

 

http://www.brightscreen.com

 

<p>

 

also available in the UK through Bob Rigby Photographic

 

<p>

 

http://www.bobrigby.com

[andrzej_poniatowski]

I have just installed a Beattie Intensreen on my Pentax 645 and it works great! Since the measurements are taken off the film plane it does not affect the readings. How it will work with Mamiya I do not know. Anyway, the Intenscreen is to be recommended - it does what they say it shall!